| 摘要 |
PURPOSE:To facilitate the separation and the purification of a lactone which is an intermediate of L-ascorbic acid useful as a food additive, by oxidizing an easily available, low-cost glucofuranose in an organic solvent in the presence of a specific metal catalyst. CONSTITUTION:A lactone of formula II is prepared by oxidizing a glucofuranose of formula I with O2 or O2-contaning gas, in an organic solvent such as ethers, amides, etc., in the presence of Pd metal and a metal or its compound selected from Pb, Tl and Hg. After the reaction, the catalyst is removed by filtration, a part of the solvent is distilled away, and the residue is concentrated to obtain the objective lactone in high purity. The amount of Pd is 0.001-1mol per 1mol of the starting compound, and the atomic ratio of Pd to the other metal is 1 to 0.01-30. The compound I can be easily prepared from glucose and acetone. |
